Chena Hot Springs is a remarkable venture, a rare combination of leisure resort, sustainable community and cutting-edge science that has seen a unique form of power generation discovered by harnessing the hot spring water.
Bernie Karl, Chena’s CEO and co-founder along with his wife, Connie Karl, has focused much of his attention on making Chena a sustainable community. To accomplish this the couple have established three greenhouses at the resort, all of which are heated using geothermal energy. This allows Chena to grow fresh produce for the resort’s restaurant and employees year-round. Even more notably, however, Bernie was responsible for the construction of the first geothermal power plant in Alaska, installed at Chena. The plant provides all of the resort’s electricity and operates off of the lowest water temperature source of all the geothermal power plants in the world, 160°F. This two-unit system has allowed Chena to reduce its energy costs from $0.30 KW/h to $0.06 KW/h.
Chena Fresh All Season Greenhouse
Chena Hot Springs Resort (Chena) erected its first greenhouse, a converted hoop house located next to the property’s outdoor Rock Lake, in the summer of 2004. This 1,000ft² structure was a test installation to determine if growing conditions could be maintained year round utilizing the geothermal resources at Chena. During the winter of 2005, Chena experienced outside temperatures as low as -56°F while at the same time, Chena was able to maintain an interior greenhouse temperature of 78°F.
In Chena’s new geothermally heated greenhouses, the concept of the hoop house was taken one step further once the company had demonstrated successful results in the original house. Two Poly-Tex, XA-300, gutter-connected greenhouses, with a total area of 4,320ft², were erected on a radiant heated concrete slab. The same 165°F water is pumped through the concrete slab. Each 30-by-72-foot greenhouse has its own environment controller and is maintained at different temperatures. Phase II included two aspects; additional heating for the winter season and a 28-foot extension to both greenhouses. Radiant fin tubes have been added along the perimeter of each greenhouse and the extension now works in the same way as the air-mixing area of the hoop house. This extension is also utilized as a work area, a display for the current projects in the greenhouse, and it offers public viewing into the grow area.
At this time, the Chena Hot Springs Chena Fresh Greenhouse produces hydroponic lettuce, tomatoes, cucumbers, peppers, fodder, and small fruits for its restaurant, employee meals and livestock. That includes more than 550 heads of lettuce a week, 25,000 lbs of tomatoes, and 275 tons of fodder produced annually.
Aurora Ice Museum
The Aurora Ice Museum was built as a way to boost tourism at Chena Hot Springs Resort, while simultaneously offering year-round employment for Steve and Heather Brice; world ice carving champions with over 21 championships between them. Chena Hot Springs erected the first version of the Aurora Ice Hotel (now renamed the Aurora Ice Museum) in January 2004. The Ice Hotel was the first of its kind in the United States, and one of just a handful worldwide, featuring a gallery and ice bar, overhead chandeliers made of individually carved ice crystals which change color every six seconds mimicking the northern lights, countless sculptures including life-sized jousting knights, an ice fireplace, and four galleries with varying themes.
Due to the high cost of electric power at the site, it was decided to use an absorption chiller design by Energy Concepts Co. and use the available geothermal resource as a power source to keep the Ice Museum frozen year-round. This chiller was a unique, three pressure design and the first of its kind to be built in the world. In September 2005, Chena Hot Springs won an award for the absorption chiller from the Geothermal Resource Council for the best new direct use geothermal project in the United States.
The Ice Museum has been a resounding success, with more than 10,000 visitors touring it each summer. The structure has also withstood high temperatures well into the 90ºF range during Fairbanks’ hot summer months.
Low Temperature Geothermal Generator
In 2004, Chena Hot Springs Resort entered into a partnership with United Technologies Corporation (UTC) to demonstrate their moderate temperature geothermal Organic Rankine Cycle (ORC) power plant technology at Chena Hot Springs Resort. The Chena geothermal power plant came online in late July 2006, putting Alaska squarely on the map for new geothermal technologies. Chena Hot Springs is the lowest temperature geothermal resource to be used for commercial power production in the world.
The concept of running a refrigeration cycle in reverse to generate power has been known for a long time. However, until now the refrigeration industry has never seriously pursued this idea. The PureCycle™ system uses waste heat exhaust gases and air cooled condenser equipment. The Chena geothermal generator takes the PureCycle™ concept one step further, generating power economically off a 120°F temperature differential between the evaporator and condenser temperature. This technology can operate off any heat source, with a minimum of 100°F temperature differential between the heat source and sink. Geothermal energy is only one potential application. Similar systems are already in operation off heat generated from landfill flares and gas turbine exhaust. Another excellent potential application is using biomass as a fuel, which is what is currently being demonstrated with the Chena Power Clean Biomass Generator.
This system provides nearly 100% of the Resort’s power, producing 400 KW net, using only clean low temperature geothermal power.
Oil and gas production also provides another possible application for this power plant. Because most oil and gas wells are quite deep, they are warmed by the natural thermal gradient of the earth. Nuisance water that is extracted along with the oil and gas can hold a temperature high enough to produce electricity. This hot water could be used to generate power directly, without impacting oil and gas production.